The elastic constants of single crystal beta-Si3N4

Using Brillouin scattering, we have determined the complete set of elastic constants of the technologically important beta-Si3N4. Availability of sing le crystals has allowed us to measure all five independent c(ij), which (in units of GPa) are: c(11)=433(3), c(33)=574(3), c(13)=127(5), c(44)=108(2), c(66)=119(4), and c(12)=c(11)-2c(66)=195(8), giving a bulk modulus of 259. Our values are compared with existing calculations and c(ij) determined fr om nano-indentation results combined with empirical relations and trends in related materials. (C) 2000 American Institute of Physics. [S0003-6951(00) 01608-9].